IC engine powered vehicles have been commercially marketed for about one hundred years and dominate the vehicle industry. Despite their widespread use, gasoline fueled IC engines have been associated with environmental problems from exhaust emissions and exhibit low fuel efficiency under light load operation and high emission under transient loads.
Electric vehicles are an alternative to combustion engine powered vehicles when minimizing vehicle exhaust emissions is a primary goal. However, pure electric vehicles developed to date have limited range of operation without battery recharging. Typical limitations also include special electric power requirements for recharging the vehicle's batteries.
Because of these pure electric vehicle shortcomings, efforts have been directed toward the development of hybrid electric vehicles. Hybrid electric vehicles are viewed as a workable compromise between conventional engine powered vehicles and pure electric vehicles. The hybrid electric vehicle in this invention is powered by batteries, and an auxiliary power unit comprised of an IC engine driven electric alternator. This combination increases driving range compared with pure electric vehicles while achieving improve fuel economy and lower exhaust emission when compared to conventional technology.
However, current hybrid electric vehicles have several limitations in the areas of noise and vibration control, emission control and thermal management. These problems limit the chance for commercial success. A major concern in a hybrid electric vehicle are annoying vibration caused by pitch, yaw, and roll torques, which are generated by cyclic irregularities of IC engines. Another concern is the high noise level of the APU when compared with electric motors. Yet another concern is thermal management of the IC engine and alternator when located in a restricted space. Still another concern of a hybrid electric vehicle is the emission control requirement. More efficient combustion and effective emission control are required to have a practical hybrid electric vehicle that meets future emission standards.
The present invention addresses these and other shortcomings, which when combined together into a highly integrated APU system by optimized design, minimizes concerns and limited acceptance of prior art.